1. Field of the Invention
The present invention relates to a stencil printing machine perforating stencil sheet mounted to a printing drum and capable of carrying out printing operation by using thereof, particularly to a stencil printing machine supplying perforated stencil sheet to a plurality of printing drums.
2. Description of the Related Art
FIG. 4 is a side view showing a conventional stencil printing machine. Stencil sheet S to be perforated is wound in a roll-like shape and is rotatably supported. The stencil sheet S reeled out from the stencil sheet S in the roll-like shape is constituted by a shape of a continuous strip. The reeled-out stencil sheet S is pinched between a thermal head 50 and a platen roller 51.
The stencil sheet S is heated and perforated by the thermal head 50 (stencil making operation). In carrying out the heating and stencil making operation, the stencil sheet S is transferred by rotation of the platen roller 51 while being brought into contact with the thermal head 50. Thereafter, the stencil sheet S is contained in a storage box 52 until finishing the heating and stencil making operation of one block by the thermal head 50. The stencil sheet S is contained in the storage boxes 52 by feeding the stencil sheet only by the platen roller 51 while upper and lower load rollers 53 and 54 disposed above the storage box 52 are stationary and pinching the stencil sheet S. Further, a common transfer path 55 is arranged at the front side of the storage box 52. The common transfer path 55 is provided with cutter means 56 for cutting one block of the perforated stencil sheet S.
After finishing the heating and stencil making operation, the thermal head 50 is moved in an upper direction to thereby release the stencil sheet S from being pinched by the thermal head 50 along with the platen roller 51. The stencil sheet S finished with the heating and stencil making operation is
In the meantime, according to the stencil printing machine shown by FIG. 4, the perforated stencil sheet S is transferred to two of the printing drums 57. Therefore, the stencil printing machine is provided with respective transfer paths 58 for feeding the stencil sheet S from the common transfer path 55 to the respective printing drums 57 and a switch mechanism 60 for selectively switching the paths to communicate the paths from the common transfer paths 55 to either of the transfer paths 58. Each of the transfer paths 58 guides the stencil sheet S between upper and lower guide plates 58a and 58b and transfers the stencil sheet S by a plurality of transfer roller pairs 59. The switch mechanism 60 is arranged between the common transfer path 55 and the respective transfer paths 58 and is provided with a shunt transfer path 62 movable by a solenoid 61. The shunt transfer path 62 moved by the solenoid 61 opens the path to communicate from the common transfer path 55 to one of the transfer paths 58 or opens the path to communicate from the common transfer path 55 to the other of the transfer paths 58.
The stencil sheet S transferred to one of the transfer paths 58 or the other of the transfer paths 58, is pinched by a clamp plate 63 disposed at the printing drum 57 at its front end, fixed to the printing drum 57, thereafter transferred by rotation of the printing drum 57 and is made to wrap on a peripheral face of the printing drum 57. Further, the stencil sheet S is cut into one block by the cutter means 56 during the transfer operation or in arrival at the printing drum 57.
Further, the stencil printing machine shown by FIG. 4 is adopted in a printing machine. A portion of a constitution of the printing machine is not illustrated. A portion of a peripheral wall 64 of the printing drum 57 is ink-permeable. There is provided ink supply means, not illustrated, for supplying ink to an inner face of the peripheral wall 64 at inside of the printing drum 57. There is provided pressing means, not illustrated, for pressing print sheet to the printing drum 57 below the printing drum 57. The printing machine rotates the printing drum 57, feeds print sheet between the printing drum 57 and the pressing means at predetermined timings and presses print sheet at image portions of the stencil sheet S mounted to the printing drum 57. Printing ink supplied from inside of the printing drum 57 passes through the peripheral wall 64 of the printing drum 57 and is transcribed from perforated portions of the stencil sheet S onto print sheet to thereby form picture.
However, according to the above-described conventional stencil printing machine, when the perforated stencil sheet S is transferred to the printing drum 57, there is needed the long transfer path 58 for transferring the perforated stencil sheet S to the printing drum 57 particularly remote from a position where the stencil printing machine per se is installed. Further, when the transfer path 58 is long, a large number of the transfer roller pairs 59 is needed. Further, there is needed the switch mechanism 60 for switching the paths from the common transfer path 55 to the respective transfer paths 58. As described above, there poses a problem that in the conventional stencil printing machine, a number of constituent parts for transferring the perforated stencil sheet S is large.
Further, when a large number of the transfer roller pairs 59 is used, there is a concern in which balance of pinch pressure at the respective transfer roller pairs 59 is delicately deteriorated and the stencil sheet S is transferred in an oblique direction. Thereby, there poses a problem that there causes mounting position failure in which a position of mounting the stencil sheet S to the printing drum 57 is not disposed at a predetermined position or wrinkle is caused in the stencil sheet S mounted to the printing drum 57.
Further, by prolonging the transfer path 58, there poses a problem that the stencil sheet S is clogged between the upper and the lower guide plates 58a and 58b or a front end of the stencil sheet is folded. The above-described problem is liable to occur particularly in the stencil sheet S used in the printing machine since the stencil sheet S comprises a sheet produced by pasting a heat-sensitive film together with a porous supporter such as Japanese paper and accordingly, the stencil sheet S is easy to fold.
Hence, in order to resolve the above-described problems, it is an object of the present invention to provide a stencil printing machine capable of feeding stencil sheet to a plurality of printing drums without causing mounting failure or transfer failure.
According to a first aspect of the present invention, there is provided a stencil printing machine comprising a plurality of printing drums arranged to be spaced apart from each other at intervals and wound with perforated stencil sheet at respective peripheral walls thereof, a stencil making unit for perforating the stencil sheet, and a moving mechanism for supporting the stencil making unit to be movable relative to the respective printing drums.
According to a second aspect of the present invention, there is provided the stencil printing machine according to the first aspect wherein the moving mechanism comprises a guide portion for supporting the stencil making unit movably relative to the respective printing drums, a drive portion for moving the stencil making unit via the guide portion, and position detecting means for detecting that the stencil making unit is disposed at a desired position.
According to a third aspect of the present invention, there is provided a stencil printing machine comprising a plurality of printing drums arranged horizontally to be contiguous to each other at intervals such that respective axis lines thereof are made parallel to each other and respective peripheral walls being wound with perforated stencil sheets, a stencil making unit for perforating and delivering the stencil sheets to be wound around the printing drums, a guide portion provided along a moving path including a plurality of mounting positions at which the stencil making unit respectively supplies the stencil sheets to the respective printing drums and supporting the stencil making unit to be capable of moving along the moving path, a drive portion provided at the stencil making unit for moving the stencil making unit along the guide portion, and position detecting means arranged along the moving path of the stencil making unit and having a number larger than a number of the printing drums provided along the moving path such that the stencil making unit can be detected to be disposed at the mounting positions and disposed at a middle position between contiguous two of the mounting positions.